Answer:
Due to stoppage of reactions.
Step-by-step explanation:
The short bursts of light during the dark period is responsible for no growth in the Xanthium strumarium plant because this short bursts of light affected the darkness which is required by the Xanthium strumarium plant for its growth. If there is no burst of light occurs, the Xanthium strumarium plant will grow normally but when Xanthium strumarium plant receives the bursts of light, the chemical reactions that needs darkness will stop and as a result no growth occurs.